So, I sea This tutorial, and I exectued this line in my terminal : sudo add-apt-repository ppa:lubuntu-desktop/ppa & sudo apt-get install lubuntu-desktop
and my left-side panel changed abit, while the Dash Home changed to become like so : http://i43.tinypic.com/2vuc0lj.png ! help !

How can I change to the ubuntu default style or ppa ! because whene I run this : sudo add-apt-repository ppa:ubuntu-desktop/ppa it gives me the follwing notice :